February 15, 2011

Laser Stops Spreading Cancer Cells

(Ivanhoe Newswire)  A new laser technique could help prevent cancer from spreading in humans.

In the study, Dr. Tuomas Tammela and his colleagues at the University of Helsinki, Finland, wanted to find out if they could help stop a cancer from spreading by using a laser therapy to destroy cancer cells lodged in lymphatic vessels.

The scientists experimented with PDT Photodynamic therapy (PDT). During PDT doctors inject a light-activated drug into the tumors and then turn an infrared laser on it. The light enables the drug to produce a type of oxygen that kills cancerous cells. Researchers tested a mouse ear as their model system.

Many tumors produce factors that help make new lymphatic vessels. The newly formed lymphatic vessels act like a highway for cancer cells to spread from the primary tumor to the regional lymph nodes from whence they can spread throughout the body.

The current practice is to surgically remove the metastatic lymph nodes and the primary tumor, but tumor cells in transit inside the lymphatic vessels are left ignored, which often results in a relapse.

Researchers injected the ears of mice with cancer cells and waited for tumors to develop. They used a light-sensitive drug called verteporfin and injected it under the skin of the ears of the mice.

Researchers found that the mice receiving PDT and surgery had a much lower relapse rate than those that underwent surgery alone.

Researchers also used a pig model to determine that PDT can target lymphatic vessels within the body and could help eliminate tumor-associated lymphatic vessels deep within the tissues of human cancer patients.

"PDT could easily be combined with existing surgical techniques to destroy the lymphatic vessels draining from the tumor, as well as the tumor cell aggregates residing within them." Dr. Tammela was quoted as saying.

SOURCE: Science Translational Medicine, February 15, 2011